Nxivm co-founder Keith Raniere is to appear in court on Tuesday in Fort Worth on charges filed by federal prosecutors in Brooklyn.
Photograph: Tony Gutierrez/AP

The leader of a self-described self-help group in upstate New York turned female followers into “slaves” who were branded with his initials and coerced into having sex, authorities alleged on Monday in a criminal complaint charging him with sex-trafficking.

Keith Raniere, co-founder of the group called Nxivm, was arrested in Mexico and returned to Texas on Monday, authorities said. He was to appear in court on Tuesday in Fort Worth on the charges filed by federal prosecutors in Brooklyn.

Raniere left the US late last year after the New York Times reported the stories of some women who defected from their secret sorority.

Nxivm’s Mexican affiliate is led by Emiliano Salinas, a son of a former president of the country. Several women who belong to the group in Mexico have traveled to Albany, the New York state capital, where they were branded, two former Nxivm members told the Times. Salinas has also denied that the sorority is affiliated with Nxivm.

According to the complaint, Raniere – known within the group as “Vanguard” – oversaw a barbaric system in which women were told the best way to advance was to become a “slave” overseen by “masters”.

They also were expected to have sex with him and do menial chores for masters, and to keep the arrangement a secret or be publicly humiliated, the complaint said.

The name of Raniere’s attorney was not immediately available. In a letter attributed to Raniere previously posted on a website related to Nxivm, he denied the practices were sanctioned by his group.

“These allegations are most disturbing to me, as non-violence is one of my most important values,” the letter said.

The complaint said that many victims participated in videotaped ceremonies where they were branded in their pubic area with a symbol featuring Raniere’s initials.

“During the branding ceremonies,” the complaint says, “slaves were required to be fully naked, and the master would order one slave to film while the other held down the slave being branded.”

Investigators said Raniere preferred exceptionally thin women, so “slaves” in the group had to stick to very low-calorie diets and document every food they ate.

A website related to the group describes Raniere as a “scientist, mathematician, philosopher, entrepreneur, educator, inventor and author” who has “devoted his life to studying the human psychodynamic and developing new tools for human empowerment, expression and ethics”.

Raniere and Nxivm have been the subject of criticism for years. In 2012, the Times Union of Albany published a series of articles examining the organization and allegations that it was like a cult.